Oil production, from which South Sudan gained 98% of its revenues on its independence, has plummeted to about 120,000 barrels a day.
PIC: South Sudanese soldiers patrol near an oil refinery in Melut, Upper Nile State, South Sudan. (AFP)
South Sudan, the world's newest country, has been mired in a devastating civil war for more than four years, with tens of thousands of people killed, nearly four million displaced and its economy in ruins.
War broke out when President Salva Kiir accused his former deputy Riek Machar of plotting a coup just two years after the country gained independence from Sudan in 2011.
With the two men to meet on Wednesday in the latest international effort to stop the fighting, here is some background.
World's youngest state
Before independence, the south of Sudan was ravaged by two civil wars (1956-1972 and 1983-2005) that pitted mainly Christian and animist insurgents in the south against Khartoum's Arab-dominated government.
Millions died in the conflicts.
A peace accord signed in 2005 by the government and southern rebels exempted the south from Islamic Sharia law and granted it six years of self-rule ahead of a referendum on independence.
The 2011 referendum went nearly 99% in favour of secession from the north and on July 9 that year, South Sudan proclaimed its independence. Kiir was sworn in as the country's first president with Machar as his deputy.
The international community -- led by the United States, China, Russia and the European Union, as well as Sudan -- quickly recognised the new African state.
Former allies turn enemies
Kiir and Machar were on the same side in the push for independence from Khartoum, but were separated by ethnic and political rivalries.
Tensions spiked when Machar -- from the country's second-largest ethnic group, the Nuer -- was fired as vice president in 2013.
His sacking came after Kiir, from the majority Dinka people, accused him of a failed coup. Machar rejected the charge, in turn accusing the president of purging political rivals.
Civil war erupts
By December 2013 the new country had descended into civil war, including fighting within the national army, undermined by differences fuelled by the rivalry between Kiir and Machar.
The conflict spread to several states and was characterised by ethnic massacres, attacks on civilians, widespread rape, the recruitment of child soldiers and other forms of brutality and human rights violations.
A 2015 peace deal saw Machar reinstalled as vice president and return to the capital, but fighting broke out in the capital Juba in July 2016, and Machar and his forces fled.
In February 2018 the United Nations said there was sufficient evidence to charge at least 41 South Sudanese senior officers and officials with war crimes and crimes against humanity.
Following more than four years of civil war, the Juba government is broke and hyperinflation -- which peaked at around 500 percent in 2016, decelerating to 155 percent in 2017 -- has sent prices soaring. The South Sudanese pound has collapsed.
Oil production -- from which South Sudan gained 98% of its revenues on its independence -- has plummeted to about 120,000 barrels a day from a peak of 350,000, according to the World Bank.
Juba, which inherited three-quarters of the former Sudan's oil reserves during independence, depends on its northern neighbour's oil infrastructure -- refineries and pipelines -- for its exports.
The conflict has also heavily disrupted agriculture, sparking a major food crisis. In 2017 South Sudan went through four months of famine, which affected around 100,000 people.
Seven million South Sudanese, more than half of the population, will need food aid in 2018, according to the UN.